1. Field of the Invention
The present invention relates generally to electrical signal recording systems, and more particularly relates to such systems employing structure for recording signals on chart paper.
2. Description of Prior Art
In known or prior art remote-position indicators, or systems for recording electrical signals, inductive receivers (transducers), bridge wire-receivers, slip-ring receivers, capacitative receivers, magnetically operated receivers are provided. Some of these receivers may be adapted for use with shaft mounted, light-coupled, position feedback systems.
In such types of remote-position indicators, transmission efficiency of the position message is a function of transition of the control signal from a mechanical into an electromagnetic value. In inductive receivers, the difficulty or problem exists that transmission efficiency can be impaired through an axle mounting (bearing) of the rotational system, through magnetic inhomogeneities of transformer material, as well as through mechanical machining efficiency of slot sides in the yoke aperture.
In resistance or potentiometer receivers, contact difficulties can arise between receiver and sliding track, as a consequence of soiling or rusting of conducting material. Cleaning, calibrating and gauging is usually frequently repeated and the slide (pilot) wire has to be frequently changed.
Capacitative remote-position indicators employ AC voltages and require adequate shielding of individual receivers, in order to avoid mutual interference of parallel channels and other outward disturbances. Operational voltage and operational frequency should be kept constant. Other remote-position indicators, have other problems.
In all of the above-described indicator systems, the recording of signals on paper or chart paper is well known. Various methods for recording these signals include a paste-paint (ball-point-pen) method, a wax writing (fusing of a waxen layer) method, a metallic layer erosion (electric sparking) method, a thin-jet color spraying method, a photo-optical method, and a pressure-sensitive marking paper (carbon-paper) method. Each of these methods or techniques have certain disadvantages which may involve poor quality of reproduction, high expense, frequency limitations, etc.
With regard to the carbon paper method, the prior art EKG and other electro-medical recorders generally employ the following technique. A galvanometer pen stylus applies pressure to the chart paper directly. The chart paper, in turn, applies pressure to the carbon paper at the point of stylus pressure, thus making an ink or carbon mark on the side of the chart paper opposite to the side on which pressure was applied. The resultant signal trace is poor quality. The chart paper thickness causes a broad spread, or contact width, with the carbon paper. This poor quality may cause masking of important signal detail in certain instances, and can be a severe problem of prior art recorders of this type. The present invention solves this problem.